Op­ti­miz­ing for­est nurs­ery pro­duc­tion

Australian Forests and Timber - - Guest Columnist - By Joachim Nach­man­sohn Nach­man­sohn Con­sult­ing & Co. Fer­til­izer Soil & Wa­ter Man­age­ment

For for­est nurs­eries it’s quite sim­ple to ob­tain all the ben­e­fits from man­ag­ing re­sources on de­mand, if you (1) fo­cus on the qual­ity, (2) stick to one sim­ple method­ol­ogy with pre­ci­sion, and (3) re­al­ize that you don’t need to grow the plantlets un­nec­es­sar­ily big.

Al­low me to il­lus­trate with a suc­cess­ful trial of both spruce and birch. The trial com­pared dif­fer­ent fer­til­izer regimes and was per­formed un­der com­mer­cial-like con­di­tions, in which a com­plete liq­uid fer­til­izer was sup­plied via the ir­ri­gation sys­tem to the peat soil in which the tree seedlings grew (see ta­ble for de­tails).

In the trial three fer­til­izer sup­ply meth­ods were com­pared:

Con­ven­tional sup­ply

A con­ven­tional lin­ear sup­ply. Ap­prox­i­mately con­stant pre-de­ter­mined amounts of nu­tri­ents were sup­plied over time, in the same man­ner and amounts as in con­ven­tional com­mer­cial pro­duc­tion in the area.

De­mand-driven sup­ply, in­tended to sus­tain max­i­mal growth

The nu­tri­ent sup­ply fol­lowed the growth pat­tern of the plant, and dosage in­creased with the growth rate of the plant. The to­tal amount of nu­tri­ents sup­plied by the end of the sea­son was less than 50 % of the con­ven­tional sup­ply.

De­mand-driven sup­ply at growth lim­it­ing rate

The nu­tri­ent sup­ply fol­lowed the same pat­tern as in pre­vi­ous method, but at a lim­ited rate that en­sured lim­i­ta­tion in the ni­tro­gen sup­ply. This meant a nu­tri­ent sup­ply over the sea­son that was about 50 % of the pre­vi­ous method (no. 2). How­ever, by the end of the sea­son a few larger ni­tro­gen re­cov­ery doses were given to im­prove the nu­tri­ent sta­tus in the tree right be­fore har­vest. This meant that the to­tal amount of nu­tri­ents sup­plied was al­most as high as in method no. 2.

The re­sults were very clear. Method no. 1 and 2 had sim­i­lar re­sult. The trees from method no. 1 were marginally taller, with a slightly larger biomass. The trees from method no. 3 reached about 2/3 of both height and biomass of those in method no. 1. All trees looked healthy by the end of the sea­son, and all were ready for plan­ta­tion in bare ground.

An­other in­ter­est­ing com­par­a­tive fea­ture was the root­size rel­a­tive to the whole tree. Method no. 1 gave the small­est rel­a­tive root size (by far), and the method no. 3 the largest (by far). Rel­a­tive root-size is an in­cred­i­bly im­por­tant trait for boost­ing growth and with­stand­ing stress af­ter re­plan­ta­tion in the bare ground.

Nu­tri­ent sta­tus in the plant is also an­other im­por­tant fac­tor when the plant­let is planted in the bare ground, as it needs im­me­di­ate ac­cess to nu­tri­ents to grow. Due to the large fer­til­izer ad­di­tions by the end of the sea­son in method no. 3, the trees from that treat­ment had the best nu­tri­ent sta­tus by far.

And let’s not for­get the en­vi­ron­ment. Method no. 1 led to the high­est nu­tri­ent losses through leach­ing without com­par­i­son.

So, in sum­mary, the de­mand-driven sup­ply meth­ods pro­vided health­ier trees with larger root sys­tems, with con­sid­er­ably less fer­til­iz­ers, and con­sid­er­ably smaller nu­tri­ent losses. And de­pend­ing on ver­sion of the de­mand­driven sup­ply, i.e. aim­ing for max­i­mum growth or lim­ited sup­ply, the trees were ei­ther grown to vir­tu­ally the same size as the con­ven­tional with the half amount of fer­til­iz­ers, or the trees were suc­cess­fully charged with a good nu­tri­ent stor­age be­fore plant­ing in the bare ground. Also, the mi­nor dif­fer­ences be­tween method 1 and 2, can eas­ily be mended with mi­nor ad­just­ments in the stan­dard de­mand-driven method.

To im­ple­ment this method in for­est nurs­ery pro­duc­tion is rea­son­ably easy. Sim­ply use a com­plete fer­til­izer that re­flects the ra­tios in the ta­ble that I have pro­vided, and fre­quently sup­ply it in doses match­ing the growth rate of the plant, that is: in­crease the doses with the same per­cent­age as the seedlings in­crease in biomass for each time unit. Re­mem­ber to keep the nu­tri­ent sup­ply all the way to trans­plan­ta­tion in or­der to en­able top nu­tri­ent sta­tus in the plants.

If you im­ple­ment this method­ol­ogy you can at­tain the fol­low­ing ben­e­fits in your pro­duc­tion: Con­sid­er­ably low­ered fer­til­izer con­sump­tion, More vi­tal plants, Stronger root sys­tem, Nu­tri­ent stor­age in the plant, En­ergy stor­age in plant, Vir­tu­ally re­move nu­tri­ent leach­ing from nurs­ery pro­duc­tion.

The main take-away from my mes­sage is that it’s sim­ple, it’s worth­while and it’s prof­itable.

Amount of nu­tri­ents in the liq­uid fer­til­izer used in the trial. The ra­tio be­tween am­mo­nium and ni­trate is 40:60. It is a com­mer­cial fer­til­izer that is based on the dis­cov­er­ies be­hind de­mand-driven fer­til­iza­tion.

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.